1. Field of the Invention
The present invention relates to high-frequency signal lines, methods for producing the same, and electronic devices, more particularly to a high-frequency signal line including a signal line and ground conductors having the signal line positioned therebetween, a method for producing the high-frequency signal line, and an electronic device including the high-frequency signal line.
2. Description of the Related Art
As a high-frequency line for connecting high-frequency circuits, a coaxial cable is typically used. Coaxial cables are widely used because they can be deformed, e.g., bent, easily, and are inexpensive.
Incidentally, recent years have seen high-frequency devices, such as mobile communications terminals, becoming more compact. Accordingly, it is becoming more difficult to provide and maintain space in high-frequency devices for disposing coaxial cables having circular cross sections. Therefore, in some cases, a high-frequency signal line having a stripline provided in a flexible laminate is used.
A tri-plate stripline is structured with a signal line provided between ground conductors. The thickness of such a high-frequency signal line in the direction of lamination is less than the diameter of a typical coaxial cable, and therefore, the high-frequency signal line can be accommodated in a small space where a typical coaxial cable cannot be placed.
Furthermore, as an invention relevant to the high-frequency signal line, a flexible board described in Japanese Patent Laid-Open Publication No. 2007-123740 is known. The flexible board described in Japanese Patent Laid-Open Publication No. 2007-123740 has openings provided in a ground layer, and can be bent readily compared to stripline structures having solid ground conductors with no openings.
However, in the case of the flexible board described in Japanese Patent Laid-Open Publication No. 2007-123740, when dielectric layers are laminated, the dielectric layers might be misaligned with one another, so that the positional relationship between the signal line and the openings in the ground layer can deviate from a predetermined relationship.